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United States Patent | 5,541,957 |
Lau | July 30, 1996 |
A data-transmitting apparatus contains first and second transmitters, a transmit transformer, and a connecting unit for coupling the transformer to an outgoing twisted-pair cable. The first transmitter filters data to produce outgoing data transmitted to the transformer at a first data rate. The second transmitter transmits outgoing data to the transformer at a different, typically greater, second data rate. A data-receiving apparatus contains first and second receivers, a receive transformer, and a connecting unit for coupling an incoming twisted-pair cable to the receive transformer. The first and second receivers receive incoming data from the secondary winding respectively at the first and second data rates. Incoming data is typically provided along data transfer paths that extend from the receive transformer in a daisy chain manner to the receivers. Data moving at either data rate can be transmitted and received without the need for hot switching in the data paths. Optical cables, including an optical transceiver, can be used with, or in place of, the twisted-pair cables.
Inventors: | Lau; Hung-Wah A. (Los Altos, CA) |
Assignee: | National Semiconductor Corporation (Santa Clara, CA) |
Appl. No.: | 260150 |
Filed: | June 15, 1994 |
Current U.S. Class: | 375/258; 375/257; 375/377 |
Intern'l Class: | H04B 003/00 |
Field of Search: | 375/258,257 370/84,85.3 333/100,119,126,131 |
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4896349 | Jan., 1990 | Kubo et al. | 375/257. |
5249183 | Sep., 1993 | Wong et al. | |
5253245 | Oct., 1993 | Fitzgerald et al. | 370/24. |
5260664 | Nov., 1993 | Graham. | |
Foreign Patent Documents | |||
0567342 | Oct., 1993 | EP. | |
0596648 | May., 1994 | EP. | |
0596523 | May., 1994 | EP. |
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______________________________________ Resistor(s) Value Capacitor(s) Value ______________________________________ RA.+-., RC 12.5 .OMEGA. CC, CA.+-. 18 pF RB.+-. 50 .OMEGA. CR.+-. 0.1 .mu.F RD.+-. 10 .OMEGA. CF 0.01 .mu.F RE.+-. 40 .OMEGA. CD 27 pF RF 75 .OMEGA. CV 100 pF RU, RW 75 .OMEGA. RRH 500 .OMEGA. RI 2.7 K.OMEGA. RH 390 .OMEGA. RL 1 K.OMEGA. RR, RS.+-. 390 .OMEGA. ______________________________________